1. Field
The present application relates to a gas sensor package.
2. Background
With regard to requirements required for a gas sensor, the gas sensor is needed to have characteristics, such as speed showing how fast the gas sensor can respond to a situation, sensibility which can respond to the detection of gas in spite of the detection of a small amount of the gas, durability showing how long the gas sensor can operate, economic efficiency showing that the sensor can be used by consumers without burdens, and the like. In order for the gas sensor to be combined with an existing semiconductor process technology, the gas sensor should have characteristics of the easiness of integration and enumeration. A home gas leakage alarm made of tin oxide (SnO2) as a material and the like come into wide use as a practical gas sensor. With regard to an operation principle thereof, the gas sensor is divided into a semiconductor type using a change of resistance values according to a change in the amount of gas and an oscillator type using a change in an oscillation frequency generated when gas is absorbed onto an oscillator, which oscillates with a predetermined frequency. Most of the gas sensors have been used as the semiconductor type having simple circuits and showing a stable thermal property at room temperature.
In order for the gas sensor to be applied to IT devices by packaging the gas sensor, analog output (resistance output) mode should be changed into a digital output (voltage output) mode. To do so, resistance, which is similar to or equal to a resistance value, should be applied to a sensing material of the gas sensor, and thus the resistance of an end of the sensing material should be changed into a voltage. However, the sensing material is problematic in that sensing efficiency is reduced because a resistance value of the basic material is changed according to a temperature, and thus an initial resistance value is not regular.
Furthermore, a gas sensor has a package structure in which a gas sensing material or a sensing chip is mounted to the gas sensor. According to the general gas sensor, a separate cap member for protecting an upper surface of the gas sensing material or the sensing chip is provided, and a mesh-shaped member formed of minute nets is provided on an upper surface of the cap member so as to allow the ventilation of gas.
In this gas sensing package for sensing gas, a height of an upper structure is increased due to the cap member and the mesh-shaped member, and an entire size of the gas sensing package is further increased up to several times to dozens of times than that of a sensor chip because a wire bonding method is used when the sensor chip is connected to an electrode part. Due to this problem, there is a limit to implement miniaturization of the gas sensor.